1. ICARUS T600: status of analysis of cosmic ray induced interactions with neutral meson production
G. Battistoni, R. Brunetti, K. Cieślik, A. Dąbrowska, R. Dolfini,
Gigli Berzolari, J. Holeczek, J. Kisiel, J. Lagoda, M. Markiewicz,
F. Mauri, A. Menegolli, P. Mijakowski, T. Palczewski, A. Piazzoli,
A. Rappoldi, G.L. Raselli, E. Rondio, J. Stepaniak, M. Szarska, A. Zalewska
28/06/2005
ICARUS Collaboration Meeting

2. ICARUS Collaboration Meeting
Contents
Search for hadronic interaction with neutral meson production:
update of scanning
Calorimetric reconstruction of e.m. showers with the new release
of ANATRA program
New (preliminary) results from ICARUS T300 data
Conclusions
(See also: ICARUS-TM/04-14)
28/06/2005
ICARUS Collaboration Meeting

3. Scanning rules for hadronic events with neutral meson production: a reminder
An interaction with a clear vertex in three views is searched;
The vertex is defined by two tracks (at least) converging
in the same point;
Two gammas (at least) must be present, generating clear showers
pointing to the interaction vertex in three views;
If just one charged track is present, the additional presence of a short,
highly ionizing proton, attached to the track end point, must be carefully
checked. If not, the event must be rejected.
Up to now, 90% of runs from ETH list including
hadronic interactions have been scanned
28/06/2005
ICARUS Collaboration Meeting

4. ICARUS Collaboration Meeting
Reconstruction tools
Identification of all hits belonging to a shower
Hit finding and reconstruction
Deposited energy reconstruction
g direction reconstruction
Evaluation of invariant mass of gg system
28/06/2005
ICARUS Collaboration Meeting

5. Shower identification
t (cm)
Hits inside the green polygonal
line only are selected for energy
reconstruction. It is really mandatory to select manually the region of shower hits when measuring real events
indicates a reconstructed hit
in Collection view.
u (cm)
28/06/2005
ICARUS Collaboration Meeting

6. Analysis routines were calibrated through FLUKA simulation
of events with p0 production in ICARUS T600
60 gg systems from 2 GeV
p- interactions in LAr
gg systems from p0 at rest
gg systems from S p0 p decay
28/06/2005
ICARUS Collaboration Meeting

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Other MC-FLUKA measurements: photons and electrons:
Number of events
Angle  [  ]
Angle  [  ]
<Energy> [ M eV]
RMS
Egen/<E>
3. Photon – 50 MeV 10 60
120 49 2
1,02 ± 0,06
4. Photon– 100 MeV 45 99 5
1,01 ± 0,06 30 90 96 4
1,04 ± 0,04 64
116
100
1,00 ± 0,03 98
1,02 ± 0,03
180
5. Photon – 300 MeV
292 9
1,03 ± 0,02
6. Photon– 1000 MeV
994 22
1,01 ± 0,02
Shower energy (MeV)
Shower energy (MeV)
28/06/2005
ICARUS Collaboration Meeting

8. ICARUS Collaboration Meeting
Measurement status
New features of software analysis:
Bugs fixed
Better evaluation of energy errors
Calculation of the distance between the starting point of each shower
and the detector walls (for fiducial volume cuts)
Up to now, the four labs involved in the analysis (Katowice, Krakow,
Pavia, Warsaw) have collected more than 200 clear events of hadronic
interactions with production of at least two e.m. showers
The total number of such events measured with the newest version of the software is ~ 120, but the work is still in progress, especially for what concerns selection criteria
In the following a few preliminary mass and energy distributions will be shown (no fiducial volume cuts applied yet)…
28/06/2005
ICARUS Collaboration Meeting

9. Invariant mass plot (1): all the gg combinations with sm/m < 10%
Fit with a Gauss function plus
a polynomial background:
mgg = ± 25.6 MeV/c2
7 events h0 candidates:
mgg = MeV/c2
RMS = MeV/c2
28/06/2005
ICARUS Collaboration Meeting

10. ICARUS Collaboration Meeting
Invariant mass plot (2): kept only two-shower events with sm/m < 10%
Fit with a Gauss function:
mgg = ± 27.1 MeV/c2
28/06/2005
ICARUS Collaboration Meeting

11. ICARUS Collaboration Meeting
Energy resolution (below 1 GeV): all measured e.m. showers (~ 300)
28/06/2005
ICARUS Collaboration Meeting

12. ICARUS Collaboration Meeting
Conclusions
The search for events with neutral meson production is almost
finished: 90% of ETH Run list scanned
More than 200 clear neutral meson production events selected
The software for the analysis has been improved and tested
through MC-FLUKA simulations
A preliminary study on ~ 120 candidate events confirms the
reliability of the analysis
In the next future data will be analyzed with more statistics
and with more refined criteria of selection. Also, new MC analysis
will be added.
28/06/2005
ICARUS Collaboration Meeting